In Solid State Commun. 91, 331 (1994), Metlushko, V. V. et al describes a thin film which is comprised of a conventional type II superconductor and which is penetrated with a periodic hole grid pattern. The flux tubes which develop in the superconductive film at a sufficiently large magnetic field organize themselves in the form of a grid (Abrikosov Grid). Based upon a measurement of the direct current conductivity as a function of the strength of an external magnetic field, that article provides information as to an interchange between the Abrikosov Grid and the superimposed artificial hole grid.
In addition, for many years high temperature superconductors (HTSC) have been known. As distinct from conventional superconductors, HTSCs can operate even at the temperature of liquid nitrogen (77 K) so that the cost of cooling can be drastically reduced. HTSCS, however, have the drawback that in the superconductive state, they have a high dissipation by comparison with conventional type II superconductors.
In the high frequency field, especially in the microwave range (300 MHz to 300 GHz), it is desirable to operate with walls of components such as, for example, resonators or hollow wave guides, as much as possible without losses of electrical conductivity of surface currents. For that purpose, significant HF characteristics of the corresponding components, for example, Q-factor, damping and the like, should be improved.
To reduce the ohmic losses of metal surfaces of HF components, it is already known to polish the surfaces, to plate them or to provide them with surface coatings comprised of a metal of high electrical conductivity (silver, gold).
It is also known, in addition, to improve the electrical conductivity of HF components by the use of superconductive surface layers. It is a drawback here that to maintain the conductive state of these layers, they must be cooled below their critical temperature T.sub.c and that requires significant expenditure.
In the electrically conductive field, strip conductors are known which are comprised of a strip carrier of an electrically conductive material and an HTSC film deposited thereon.
In the measurement field, SQUIDs (SQUID: superconductive quantum interference device) are known for high sensitivity measurements of magnetic fields. With HTSC SQUIDS, it is a drawback that the measurement sensitivity is limited by a relative high low frequency noise.